1. Field of the Invention
The present invention relates to shutters and in particular to shutters of the roller type having improved resistance to storms and break-ins. Furthermore, this invention relates to a shutter having improved retraction capability.
2. Description of the Related Art
Conventional roller shutters are designed to provide security from break-ins or protection from storms. The shutters must maintain appropriate structural integrity while extended in order to provide security and protection, but the design of a roller shutter must also allow a user to conveniently extend or retract the shutter on demand. Even though conventional roller shutters may need to be extended and retracted frequently or unexpectedly, such shutters have been prone to jam and/or snag. In addition, various factors influence the strength of a shutter and its ability to withstand forces of nature and attempts by intruders to break in through the aperture enclosed by the shutter. The material choice for fabrication of the shutter is one such factor, as is the type of articulation between shutter slats. In addition, a shutter may be strengthened by increasing surface area contact of each shutter slat with a guard, typically a track that runs the full length of the building aperture covered by the shutter. Unfortunately, this surface area is limited by the requirement that the slats of a roller shutter must be capable of conforming to a roll, for convenient storage.
One such conventional roller shutter employs a single c-shaped boss located inside the hollow body of the shutter, into which a retaining screw may be inserted. The retaining screw then holds the slat in a fixed position within the guard, allowing the roller shutter to slide up and down the guard during retraction and extension, respectively, while purportedly preventing the roller shutter from undesirably disengaging from the guards. This shutter differs from the present invention because it bears only a single boss and does not employ a retention plate.
One result of this configuration is that the individual shutter slats easily jam during extension and retraction of the shutter. The single retention screw provided in each shutter slat allows the slat to wiggle undesirably within the guard, particularly when the articulation between slats is loose or when there is otherwise play between slats.
U.S. Pat. No. 6,631,749 to Zabala teaches a roller shutter in which each slat has one or more transverse ribs for support, as well as two sets of internal brackets running the length of the slat, in which retainers, or retaining screws, are disposed. The retainers of each slat slide along the guard assembly as the roller shutter is extended and retracted, and provide support to the roller shutter by restricting the motion of the slats. The '749 patent is different from the present invention because it requires support ribs that are separate and distinct from the brackets into which the retainers are received. Furthermore, the '749 patent does not teach or employ a retention plate to maximize surface area contact between the shutter slat and the guard.